intermittent starting on 98

[merak2310]

Have had problems recently with my 98 Sport not starting after hot. Have seen a ton of people here with the same problem Anyone changed the fuel pump yet? I'm goin to this weekend, just wanted to check anyone's luck. I noticed when it won't start and I release the schrader valve there is air in the line. On a different note, just changed my IAC motor because it wouldn't idle and that cured that...FYI. Anyone's help would be appreciated. Thanks.

[brunnj]

Originally Posted by merak2310

Have had problems recently with my 98 Sport not starting after hot. Have seen a ton of people here with the same problem Anyone changed the fuel pump yet? I'm goin to this weekend, just wanted to check anyone's luck. I noticed when it won't start and I release the schrader valve there is air in the line. On a different note, just changed my IAC motor because it wouldn't idle and that cured that...FYI. Anyone's help would be appreciated. Thanks.

I have the same problem on my 99 Mercury Mountaineer with 5.0L V8. Difficult to start at different times but will eventually start every time. Once it is started, it runs great. I have checked the fuel pressure at idle and it is about 64psi. After shutting the engine off, the pressure drops to 0 psi in about 1 minute or less. I'm not sure if it is the fuel pump or pressure regulator. Two service writers from two different local dealerships have told me it is the fuel pump since it is responsible for holding pressure when the engine is not running.
I purchased a replacement pressure regulator and it doesn't match up with the regulator that is pictured in my Haynes repair manual. According to Haynes, the regulator is just behind the intake manifold at the back of the engine and can be removed by taking out two retaining bolts. The replacement regulator's design supports this but the part that I am looking at does not have two retaining bolts. It has a vacuum port at the top and appears to be pressed onto the fuel rail. It is silver in color. Anyone know if this is actually the regulator or a fuel pulse modulator, as I read somewhere else. Thanks for any help.

[way2old]

Your fuel pressure should be between 30 and 45 psi. If you have 64psi, the regulator is bad. If the fuel pressure bleeds off as fast as you say, the check valve in the pump is probably bad also. Step one from Ford Manual:

For Mechanical Returnless Fuel System with fuel pressure greater that 448 kPa (65 psi). REPLACE fuel pressure regulator in fuel tank.

If you are running that pressure, more than likely it is in the tank. The part you purchased is the fuel pulse dampener. The regulator is in the tank. Have fun.

[brunnj]

Thanks for the reply way2old.
I was told by a service writer at a local Ford dealership that the 64psi of fuel pressure is normal. He said if the pressure regulator goes bad then the pressure will rise to around 100psi. He told me if I am losing pressure as soon as I turn the engine off then it is the check valve in the fuel pump (same thing you said). I decided to take the vehicle to a local shop and pay to have the fuel pump replaced ($450). It fixed the problem. The vehicle starts up every time now as soon as I turn the key.

I word of warning. If you are working around the fuel pulse damper (which is located on the fuel rail between the back side of the intake manifold and the firewall), be careful not to break the hard plastic vacuum hoses (white and green if I remember correctly) in that vicinity. I think the mechanic, or I, accidentally broke the one going to my EGR vacuum control solenoid. It caused the engine to miss at a low steady speed and eventually set the same DTC you'll get if your DPFE sensor goes bad (EGR flow insufficient). Needless to say, I was in the process of replacing the DPFE sensor when I discovered the break. I bridged the two broken pieces and replaced the sensor and the vehicle is running fine (can't hurt to have a new sensor in place anyway).

Hope this info helps anyone else out there having the same problems.